Detection of potyviruses infecting Iranian common beans using broad-spectrum antibodies and universal primer pairs

Six provinces of Iran were surveyed during 2012–2014 to detect potyviruses infecting common bean crops. A total of 277 leaf samples were collected from bean plants and some other legumes as well as weeds and wild legumes showing virus-like symptoms. Enzyme-linked immunosorbent assay (ELISA) using broad-spectrum potyvirus antibodies gave a positive reaction with 63 samples (22.7%). Moreover, a mixed colony of aphids (Aphis craccivora and A. fabae), collected from a locust tree plant (Robinia sp.), transmitted a potyvirus to young healthy bean plants; the infection was confirmed through serological assays. Partial nuclear inclusion b (NIb) and coat protein (CP) regions of the genomes of 19 ELISA-positive samples were amplified by reverse-transcription polymerase chain reaction (RT-PCR) using NIb and NWCIEN (or WCIEN) universal primer sets, respectively. Potyvirus species identification was confirmed by BLASTN and phylogenetic analyses followed by ELISA tests using virus-specific antibodies or biological assays. The results clearly showed the presence of Bean common mosaic virus (BCMV), Bean common mosaic necrosis virus (BCMNV), Bean yellow mosaic virus (BYMV) and Wisteria vein mosaic virus (WVMV) in the samples tested. Non-specific amplification of a Cucumovirus genome by using NIb primers was also recorded. The results showed the natural occurrence of a new potyvirus species (WVMV), and a new host for BYMV (Trifolium repens) in the mid-Eurasian region of Iran. Our findings indicate the capacity of the universal detection systems for fast and accurate detection of legume potyviruses in the country and for use in routine diagnostic assays.